The ptrace APIs also can’t write to read only memory, at least not on modern Lin... | Hacker News

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woodruffw on Jan 29, 2022 | parent | context | favorite | on: On self-modifying executables in Rust

The ptrace APIs also can’t write to read only memory, at least not on modern Linux running on CPUs with modern MMUs. But SMC doesn’t require that, because you can always map (or remap) executable pages as writable.

Executable code is only read-only by default, you can always change that (or just not do it, in the case of a JIT).

comex on Jan 29, 2022 [–]

> The ptrace APIs also can’t write to read only memory

Sure they can.

https://stackoverflow.com/questions/49442087/how-does-ptrace...

woodruffw on Jan 29, 2022 | [–]

Huh, this is news to me! I always thought that ptrace temporarily changed the page's permissions, rather than bypassing them entirely. My mistake.

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